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I am building a window bench seat in my home. The bench will cover 2 of my electrical receptacles. My plan is to extend the wires from each of the original blue 1 gang boxes and feed them into new 1 gang boxes I'll mount to the front of the bench and I just want to make sure I'm doing everything properly.

The bench extends 23 inches out from the wall. Can I simply just extend the live, neutral, and ground wires from the first box to the second using wire nuts to attach new wire? I'd cut about 36 inches to extend the 23 inches of the bench plus give me some slack to extend beyond the new boxes. I believe it's standard to allow enough slack to extend at least 6 inches beyond the box. There are 2x4s that run the width of the bench I can run the wires across to the new receptacles using eye bolts.

I believe the circuit is a 15-amp. If so I have 14 gauge solid core wire already I can use. If it's 20-amp I'll have to stop at the store and pickup 12 gauge. Is this the proper way to do this or am I missing an important safety step?

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  • Since you wrote "2x4s," "14 gauge" and "inches" I will assume you are in the US or Canada. In the US, electrical codes require wire connections to be done in junction boxes and junction boxes to be accessible (not covered by a built-in bench). The electrical code in Canada is mostly very similar to US codes. In the US, every state and many cities and counties have their own building code. Some are quite strict about changing wiring without a building permit. – Charles Cowie Jul 18 '18 at 15:46
  • Is there any particular reason you can't just use a standard extension cord? – Felthry Jul 18 '18 at 15:53
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    @Felthry, if the receptacle is covered by a built-in bench, making it inaccessible is a code violation. Using an extension cord as a substitute for fixed wiring may also be a code violation. Eliminating a receptacle, thus making the distance from some wall area farther from the nearest receptacle may be a code violation. – Charles Cowie Jul 18 '18 at 16:01
  • Exactly - it is against code to have any hidden electrical junctions. – The Evil Greebo Jul 18 '18 at 17:01
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    So the top of the bench is 6 pieces 3/4" plywood. Would it be acceptable to mount the ones above the outlets on a hinge instead of screwing them to the bench so the outlets are accessible? – jwaldorf2 Jul 18 '18 at 17:09
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As the good commenters mentioned you cannot bury the junction box, it must remain accessible. A hinged bench seat sounds like a great workaround. That space under the bench could be considered part of habitable space though, so the cable would need to be protected in a raceway or conduit. It would be acceptable to build a short raceway out of 2x4s.

But if you're going to have a hinged bench anyway, would it be so bad to just leave the receptacles as-is, and when you need them open the bench? You could leave a little notch in the back of the bench so you could close it after plugging in the vacuum or whatever you'll be plugging in. Or run a power strip out of it.

[EDIT: A cable coming out the blue box and into the void behind the wall could route into a raceway that terminates into the same wall void, adjacent to the blank cover. The reason you cannot have a cable run out of a hole in the blank cover itself is that would be unprotected. Protecting that cable coming out the coverplate makes the junction box inaccessible. What you could do instead is use an extension box that you could screw conduit into: enter image description here The box extension comes with some plugs to plug one of the holes, and the other hole would be your plastic or metal threaded conduit terminal adapter (must connected ground to it if its metal).]

  • Using just the original receptacles would work OK for a vacuum cleaner. But if, for example, you want to plug in a radio or a fan and sit on the bench while using it then losing 2' of the cord to the distance under the seat wouldn't work so well. – manassehkatz Jul 18 '18 at 17:36
  • Would I need to buy a blank faceplate and drill a hole in it for the wires coming out of the junction box or can I just leave that open? I'm also making a cushions out of 3" foam to run the full length of the bench. Probably 3 cushions, 2 for the ends over the outlets and a larger middle section. Having to remove the cushions and lift up the top of the bench every time I want to use the outlets is a hassle I'd like to avoid if I can. – jwaldorf2 Jul 18 '18 at 17:38
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    @jwaldorf2 I edited my answer. I understand the hassle. A power strip may be the best option without requiring rewiring. You could mount it just under the front of the bench. If you still want to re-wire permanently, just keep in mind what a buyer's inspector might say about the work when you want to sell your house someday eg make sure its up to code and done in a neat and workmanlike manner – freshop Jul 18 '18 at 22:23
  • Accepting this answer. Thanks for all your comments. My plan will be to splice new wire in the current box and run a raceway from it to the the location of the new receptacle. I'll allow a large panel of the bench to be removal to provide easy access to what is now a junction box. Thanks everyone. – jwaldorf2 Jul 19 '18 at 14:37
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Code requires you have a receptacle every 12 feet along the wall (or to be more precise, located such that you can place an appliance with a 6' cord anywhere you desire without use of extension cords). You need to comply with that regardless.

I don't agree that an "access hatch" is sufficient; Code has certain rules for just how accessible junction boxes must be.

Surface conduit

If you can make the old receptacle boxes accessible enough for Code, then you can extend off them via surface conduit such as Legrand Wiremold. You start with a "surface conduit starter box" then use surface conduit to go to surface mount junction boxes. They even make slimline receptable boxes only 1" thick.

Be careful to buy surface conduit at a real electrical supply house, the kind in the industrial district and no pretty mall ambience. You will need some of the oddball parts, and big-box stores just don't stock the slow sellers. The electrical supply will carry every part, or none at all.

Permanently move

Retire and permanently remove the receptacles, and install new ones in new locations.

Start by looking at products called "Old Work" junction boxes. Avoid the ones that only attach to drywall; drywall being essentially chalk wrapped with glued paper, they aren't strong enough to survive a wrestling match of trying to insert or remove a stiff 3-prong plug in a new socket. Look for the ones that attach to joists with stout screws. Big bonus points for metal boxes. Metal boxes don't burn.

Now with both Code spacing and "old work" box design in mind, select new locations for receptacles that are needed, or that you want.

No doubt the receptacles are wired in a string and there is already a route for Romex/NM cable through the various joists. Once you have the new boxes sited, push the cables out of the old boxes and demolish and remove the old boxes. Then do some workable combination of

  • Use the old route of the existing cables to run an entirely new cable run between your new boxes, i.e. fishing a new cable. Or
  • Join the old cables with a UL-listed-for-the-purpose splicing device, that is designed to splice inside walls without a junction box. There happens to be one, made by Tyco.

At this point the old junction boxes are gone (you needed to in order to get access to fish or splice) and there are gaping junction-box-sized holes in your drywall. Patch them in the normal way, or since the old junction boxes were mounted on studs, screw a chunk of wood into that stud, so that it can support a piece of drywall where you need it. Predrill holes to be sure the screws won't split the wood. Patch and mud; paint if you care.

The patching is mainly to protect the fire-stop rating of the wall. Being a fantastic firestop is drywall's one redeeming quality.

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